track width variance due to square setup

pkimM3r · 03-26-2014, 06:56 PM

I know there is a lot of square setup conversations, but I don't think I've seen one about the effects it has on overall track width.

Stock zcp setup....track width is front = back?

when you go square, the 275 / 18x10 combo in front brings out the wheel +19mm....add a 5mm spacer and you are now +24mm.

track width up front is now wider than the rear....guess i need a 24mm spacer in the back

OR, am I wrong about the stock track width and going square should make it closer to even front to back.

Billj747 · 03-26-2014, 07:06 PM

wider front = more front grip = good

jphughan · 03-26-2014, 07:48 PM

I ran these numbers once using 220Ms and 359Ms as baselines to determine changes in track and the outboard positions of the wheels to predict appearance and handling changes when I was looking at a square setup. Surprisingly, ZCP wheels create a NARROWER track than 220Ms despite their extra width because of their offset, even though the ZCP press releases talks about aggressive offsets. I don't know the starting track widths offhand (though that should be in the M3 Supplement at the back), but here are the relative changes. Sorry for mixing inches and millimeters, did it because offsets are in millimeters and wheel widths are in inches:

220M Fronts: 19x8.5 offset +29
220M Rears: 19x9.5 offset +23
APEX EC-7s: 18x10 offset +25

From 220Ms to EC-7s:
Front track: +8mm
Front wheels move outboard 0.9"
Rear track: -4mm
Rear wheels move outboard 0.17"

359M Fronts: 19x9 offset +31
359M Rears: 19x10 offset +25

From 359Ms to EC-7s:
Front track: +12mm
Front wheels move outboard 0.74"
Rear track: Same
Rear wheel positions do not change

Triple M · 03-26-2014, 09:50 PM

Glad you brought this topic up. I posted something similar recently titled "true square setup". That's what I was getting at, which is overall front and rear track width in relation to contact patch. I had wanted to go a little wider on my 18 x 9.5 (265 to 275) up front, while going a size smaller (285 to 275) in the rear on my 80 x 10.5. Me and Bigjae were actually discussing this recently at COTA when we considered oem numbers which is looked up, and found to be the SAME 1.54m (60.6in) both front and rear despite factory "staggered" setup. Wheel offset is an important factor. With addition of spacers (needed at times), those values change even more. I think bottom line is having more contact patch up front can never hurt as long as it doesn't affect turn-in/steering characteristics. This is a poorly understood topic( I'd be the first to admit I'm still learning), just ask the folks at APEX wheels how many begillion questions they get

pkimM3r · 03-26-2014, 11:51 PM

Quote:

Originally Posted by Triple M

Glad you brought this topic up. I posted something similar recently titled "true square setup". That's what I was getting at, which is overall front and rear track width in relation to contact patch. I had wanted to go a little wider on my 18 x 9.5 (265 to 275) up front, while going a size smaller (285 to 275) in the rear on my 80 x 10.5. Me and Bigjae were actually discussing this recently at COTA when we considered oem numbers which is looked up, and found to be the SAME 1.54m (60.6in) both front and rear despite factory "staggered" setup. Wheel offset is an important factor. With addition of spacers (needed at times), those values change even more. I think bottom line is having more contact patch up front can never hurt as long as it doesn't affect turn-in/steering characteristics. This is a poorly understood topic( I'd be the first to admit I'm still learning), just ask the folks at APEX wheels how many begillion questions they get

In my quick google search when i posted this i too also saw overall track width front and rear to be equal with the difference in wheel width - this is prob why they went with this setup. Hence my +19mm wider in front now (using wheel calculator) due to the change in size but the rears staying the same.

pkimM3r · 03-26-2014, 11:54 PM

Quote:

Originally Posted by Billj747

wider front = more front grip = good

Good to hear from a pro! But are there any designs that have purposely had the front track wider than the rear? Or is this not done strictly because of safety measures.

Would sort of be driving a 911 in reverse the whole time. Engine in front, wider front, narrower back.

pkimM3r · 03-26-2014, 11:56 PM

Quote:

Originally Posted by jphughan

I ran these numbers once using 220Ms and 359Ms as baselines to determine changes in track and the outboard positions of the wheels to predict appearance and handling changes when I was looking at a square setup. Surprisingly, ZCP wheels create a NARROWER track than 220Ms despite their extra width because of their offset, even though the ZCP press releases talks about aggressive offsets. I don't know the starting track widths offhand (though that should be in the M3 Supplement at the back), but here are the relative changes. Sorry for mixing inches and millimeters, did it because offsets are in millimeters and wheel widths are in inches:

220M Fronts: 19x8.5 offset +29
220M Rears: 19x9.5 offset +23
APEX EC-7s: 18x10 offset +25

From 220Ms to EC-7s:
Front track: +8mm
Front wheels move outboard 0.9"
Rear track: -4mm
Rear wheels move outboard 0.17"

359M Fronts: 19x9 offset +31
359M Rears: 19x10 offset +25

From 359Ms to EC-7s:
Front track: +12mm
Front wheels move outboard 0.74"
Rear track: Same
Rear wheel positions do not change

Yeah i got the slightly different numbers using the wheel calculator and then factor in a spacer (thanks kw) but which negate each other since both front and rear are the same size. I'm just wondering if it would be useful to run a wider spacer in the rear to negate some of this effect. Eg 10-12.5mm spacer in back vs 5mm in front to offset the gain in front track width.

bigjae1976 · 03-27-2014, 04:53 PM

Quote:

Originally Posted by SlowSaloonM3

Good to hear from a pro! But are there any designs that have purposely had the front track wider than the rear? Or is this not done strictly because of safety measures.

Would sort of be driving a 911 in reverse the whole time. Engine in front, wider front, narrower back.

I'm sure there are designs that spec a wider front axle but I would imagine that BMW wants a even look for esoteric reasons for the mass.

I run a front 12mm spacer on my E46 M3 with square 17x9.5 et35 ARC8s so the front tires clearly stick out farther than the rears. Doesn't look as awesome but the front end is more responsive on turn in.

Triple M · 03-28-2014, 09:41 PM

This concept really does made me wonder how the nissan delta wing functions. The trend for front engine car to run wider track is making a lot more sense. Getting my 18 x 10 square setup ordered. That E46 M3 definitely definitely looked aggressive with the wider front. I'm going to slap 275 upfront for now on my 18 x 9.5 to make them "less staggered" even though it hey aren't really squared.

03-26-2014, 06:56 PM	#1
pkimM3r Banned 257 Rep 7,298 Posts Drives: m3 saloon in granny mode. Join Date: Dec 2009 Location: lost angeles iTrader: (0)	track width variance due to square setup I know there is a lot of square setup conversations, but I don't think I've seen one about the effects it has on overall track width. Stock zcp setup....track width is front = back? when you go square, the 275 / 18x10 combo in front brings out the wheel +19mm....add a 5mm spacer and you are now +24mm. track width up front is now wider than the rear....guess i need a 24mm spacer in the back OR, am I wrong about the stock track width and going square should make it closer to even front to back.
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03-26-2014, 07:06 PM	#2
Billj747 Captain 176 Rep 658 Posts Drives: Everything Join Date: Feb 2009 Location: SoFlo iTrader: (0)	wider front = more front grip = good
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03-26-2014, 07:48 PM	#3
jphughan Brigadier General 621 Rep 4,473 Posts Drives: '16 Cayman GT4 Join Date: Mar 2011 Location: Austin, TX iTrader: (0)	I ran these numbers once using 220Ms and 359Ms as baselines to determine changes in track and the outboard positions of the wheels to predict appearance and handling changes when I was looking at a square setup. Surprisingly, ZCP wheels create a NARROWER track than 220Ms despite their extra width because of their offset, even though the ZCP press releases talks about aggressive offsets. I don't know the starting track widths offhand (though that should be in the M3 Supplement at the back), but here are the relative changes. Sorry for mixing inches and millimeters, did it because offsets are in millimeters and wheel widths are in inches: 220M Fronts: 19x8.5 offset +29 220M Rears: 19x9.5 offset +23 APEX EC-7s: 18x10 offset +25 From 220Ms to EC-7s: Front track: +8mm Front wheels move outboard 0.9" Rear track: -4mm Rear wheels move outboard 0.17" 359M Fronts: 19x9 offset +31 359M Rears: 19x10 offset +25 From 359Ms to EC-7s: Front track: +12mm Front wheels move outboard 0.74" Rear track: Same Rear wheel positions do not change __________________ '16 Cayman GT4 (delivery pics, comparison to E92 M3 write-up) Gone but not forgotten: '11.75 M3 E92 Le Mans \| Black Nov w/ Alum \| 6MT (owned 5/2011 - 11/2015)
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03-26-2014, 09:50 PM	#4
Triple M Doc Rebel! 31 Rep 324 Posts Drives: Fire Orange M3, X5M, Blk 135 Join Date: Oct 2011 Location: Vegas Baby! iTrader: (0)	Glad you brought this topic up. I posted something similar recently titled "true square setup". That's what I was getting at, which is overall front and rear track width in relation to contact patch. I had wanted to go a little wider on my 18 x 9.5 (265 to 275) up front, while going a size smaller (285 to 275) in the rear on my 80 x 10.5. Me and Bigjae were actually discussing this recently at COTA when we considered oem numbers which is looked up, and found to be the SAME 1.54m (60.6in) both front and rear despite factory "staggered" setup. Wheel offset is an important factor. With addition of spacers (needed at times), those values change even more. I think bottom line is having more contact patch up front can never hurt as long as it doesn't affect turn-in/steering characteristics. This is a poorly understood topic( I'd be the first to admit I'm still learning), just ask the folks at APEX wheels how many begillion questions they get
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03-28-2014, 09:41 PM	#9
Triple M Doc Rebel! 31 Rep 324 Posts Drives: Fire Orange M3, X5M, Blk 135 Join Date: Oct 2011 Location: Vegas Baby! iTrader: (0)	This concept really does made me wonder how the nissan delta wing functions. The trend for front engine car to run wider track is making a lot more sense. Getting my 18 x 10 square setup ordered. That E46 M3 definitely definitely looked aggressive with the wider front. I'm going to slap 275 upfront for now on my 18 x 9.5 to make them "less staggered" even though it hey aren't really squared.
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